Process for preparing a bleached keratin meal



July 19, 1949. R.` NEIGER ET AL PROCESS FOR PREPARING AYBLEACHED KERATINMEAL Filed July 8, 1946 mme:

and 1yaelav Nachazel .y MKM Y m'n/ Attorney:

.Withoutfseoiumhypes-.1in ite -enablcsi products- `.te-'fleeY obtained;which ,site feel-lent. translucent .or transmettent; .including-S@with`theusua1;articia1 resins. These-products Patented July 19, 199492,476,758 PRQQESS FOR PREPARNG A BLEACHED KERATIN Richard.'lseifgergMaryport England, and* Vaclav N achazel, 'Izlove, near Podmoldy,'GzechoslonWikia', assifg-nors yto Messrs. Hornilowa Limited,

-Maryiort, England, a British-company Application July 8, 1946,'.SeralNo, 681,799.3@ .In v4.Great Britain April 2,3, .1945

Sect-ien' 1f, Public Law 690, AugnstS, .1946.

:Patent expires April' 23, 1965 Claims. (Cl. ZBO-4123.7)

VThis invention relates tothe process: for. preparing a.bleachedzkeiatin. mealxina fQrm suitable for use in. making.. moulded.articles such as. .-buttons, buckles., `electrical. insulators andtimings. .Keratin is generally. deriyed from `.ground horns. V'and hoofsof ,animals but the vgroundproduct .requires purication before it canmbeused. for making. .high class.: ,moulded articles. .When Jrequirecil.for making translucent mouldings vthe keratinmustbe; bleached in orderpatterns by`snraa.1e through Stencils, sifting that it may be light inshadeor .coloured to a Y fgrinding process. in` which..alargeproportion. of

the .impuritiesacan be eliminated. :further object is. to zprovide ay.simple bleaching process .for :theselectively groundproducbinvol-.ving.only a reducing .treatment :The selective vgrindingprocess.according tothe invention .consists in.-,cr.ushing. theft-aw.I material such ashoofs, and. thensubjectingthe product to, a selective grinding, .and.S-itl'lg.processV in which the impurities.. are largely removed withthepartcles which pass through-thener meshes of the sieves, while the,coarser .particles .of

keratin of a higher degreeof .purity are separated Vand Asuhiected to afurther staeeceferindirle.

The bleaching process .according to the invention consists in .Steepingthe selected keratin product of substantial pur-.ity .incinte-ammonia.for some hours, separating ,it trom the alkaline solution, acdulating.it and bleachmg, with the aid ofr a reducing agent.

It has been Yfound that a selective grinding and sifting process whichremoves .a largeproporton ofthe impurities, .followed .by a -fsimpilereducing .treatment in which the material is Lfirst acted upon by dilutelammonia Solution., then neutral- ;ised and treated with areducing agentsuchas .sodium formaldehydesulphoxylic acid. withv 0r acid. medium,

Ltend..ftheutselxies..toeccitante.or. therfenmationfef through zstencils.. and s0 .fcrth, .01 .cf course enaque -monldings can also bemade Vfrom them .by the addition ,of pigmenting materiale if dee sired.

.Ithas been that therawmaterial. e.. ghoofs, contains a .certainyariable pencentage 0.1 impurities both-.organic and inorganic, unich,if not. removed. .from .the around..ma.terial,` .contaminate in andare.- also veryA oiiicult to bleach by .any known process.Y"Iheimpilrities, @van after Athe bleachnacan. loev feund as Qatk Sneaks-thfroushout ther material.. and they impair the uniformity of themouldinaas well as the colour.- '-IneyA .are also .objectionable becausethey ,may .have an .adverse effect .on the physical qual-.ities .of themouldines. -lhese impurities may be prea- .entin the. term .of .dirt*.adhering.- to or embedded the; surface. of the hoois,..or asincrustationa Thefformerzare v ery. difcult ammore by Wash.- fing, thelatter, .of course,..cam19t be removedV by .washing at all.v In `orderremoyethese im.- pur-ities. the renewing methods. haye been .develped:

A-fterbeing'washed the hoofs are dried. in pref.- erably. verticaldrying. `shafts.. for approximately 24 to 3.6 hours. at temperaturesbelow the boil;- Ving .point .of water, .up to,y about 89 .or 90 C.,and-then allowed-to..cooi.-down to room. .temperature. kBy .this.process most .ofthe free. water is .removed and. .the .subsequent.crushing requires .-sulostantiallyr less. time thannwithout .theprevious drying. At Athesame time the. and: foreign matter .are`loosened, part` pee1s..o ff..and: is. sep.- arated. from-the hoofs when:passing .over .-sieyes at the bottom of the .shaft through Ywhich .thenner foreign .matter .falla This mechanical -nurlflcationmay beimnmyedby thawing. off air tlncrleh theoryine shafts.. '.lhe hoois arenrst .erusned :and .instead .of grinding the crushed; hcofs Singlegrinder 11.1. One .operatlon until: thev .desiredt -neness. is reached,the jglnding. is .electedin. .a Series. of .two or. mote .e .nera each.with its .own :selfecontained re.- ceiyaraeletators, andsieyecompartments givins what maybe termed.. .a selective Yerirleing process.

"The crushing. is` preferably effected. int .a hammer mill which-breaks@or .granulates 1the nente. and. .the grinding eiected preferahlyY.t1-.ish zspeecl --impact grinders. or pulverisers .auch as nin .millsso that the breaking elect .each

the `vctmtrolled .by varying the :speed-0f rotation. The .selectivegrinding-:procese is based 'onztheviollowine theory I The crushing ofthe hoofs is facilitated by the presence of encrusted or embeddedimpurities, which constitute points of weakness in the hoof structure sothat impact fracture occurs readily at those points where foreign matteris present. The liberated impurities then pulverise much more quickly toa finer powder than the hoof fragments. The material is then passed overa number of sieves of different mesh, and the finer particles containingmost of the impurities and dirt fall through the sieves and are soseparated from the coarse material which is then conveyed to the nextgrinder and the whole process is repeated. It is advisable to grind thehoofs firstly in one or more grinders with a speed of 2000 to 3000 R. P.M. and then in one or more grinders at a higher speed, say 4000 to 6000R. P. M. The ground material which falls from each of the machines ispassed through a separate set of elevators and sieves enabling thevarious grades to be differentiated both with regard to their mesh sizeand purity. It is very important to start the grinding at lower speedbecause the pulverizing action is then gradually increased and favoursthe selective grinding and separation. The further the process advancesthe cleaner do the separated materials become.

A suitable lay-out of plant for this purpose is indicated in theaccompanying diagram which shows a flow sheet of the plant. The rawmaterial such as hoofs is fed through a preliminary Washer a to driers bthrough which hot air from a fan c is passed. The dried material israised by an elevator d and delivered to a magnetic separator m1 and ahammer mill or crusher e. The product from the mill e is raised by anelevator f and delivered to rotary sieves g1, g2, of different degreesof fineness, the flne through products which contain a good deal offoreign matter being collected in sacks s1, s2, while the overs arecarried by elevator i and delivered to bins k1. A fan p1 extractsdust-laden air from the input end of elevator f and the rotary sievesg1, g2, the dust being ycollected in dust collector o1 which delivers itto a sack h1. From bins k1 the material passes through another magneticseparator m2 to an impact'pulveriser l1 which may run at say 3000 R. P.M. Part of the output from pulveriser l1 goes to a cyclone-typeseparator n1 from which air is extracted through a dust collector o2 bya fan p2, the dust being collected in sack h2. Another part of theoutput goes to one of a series of elevators q delivering the product toone of the plansifters r1 to r6, these being sift- `ing machines havingmultiple sieve units which are horizontally agitated.

Additional grinding bins k2 and k3l are provided which receive coarsermaterial fed back as v overs from some of the plansifters r1 to r6 bycertain of the elevators q. The output from the bins k2 and k3 isdelivered past magnetic separators m3 and m5 respectively to impactpulverisers F and Z4 running at say 4000 to 6000 R. P. M. and connectedto cyclone-type separators n and n". The major part of the output ofpulverisers l2 and Z4 goes to the elevators q and the plansifters. Anintermediate magnetic separator m4, pulveriser Z3 and cyclone-typeseparator n3 operate upon coarse overs fed back from some of theplansifters r1 to T5, and return part of the pulverised product to theplansifters again. The pulveriser Z3 may run at say 6000 R. P. M. Thedust-laden air from separators nl and n2 goes to dust collector o2 andfan p2, while dust-laden air from separators n3 and n4 goes to dustcollector o3 and 4 fan p3. The dust from collector o2 is received insack h2, and the dust from collector o3 goes to sack h3. The gradedproducts from the plansitters r1 to r6 are collected in sacks s3 to S10.This flow sheet is to be regarded only as one example of a suitableplant.

The products delivered from the various plansifter compartments intosacks s3 to SB are of different grades and purity depending upon thesteps of grinding and sieving which they have passed through. The puresttypes are well adapted for bleaching, compounding with articial resinsand moulding to give products of a high translucency, suited forcolouring, and for further treatment such as surface spraying or siftingthrough stencils to produce articles resembling natural horn or othermaterials. The less pure products, as well as those received in sacksh1, h2, h3 and s1, s2 can be mixed with articial resins and colouringmatter to produce good quality opaque articles but are not pure enoughto justify refining and bleaching.

It has been proved analytically that the ash content, i. e. theinorganic material in the product received in the sacks s3 to s1decreases from about 2.5% down to 0.2% in proportion as the grades ofthe material improve in purity in the course of the selective grindingand sieving process. The material so produced is cleaner and moreuniform than the products obtained by the usual grinding methods, andrepresents an ideal starting material for the further refiningtreatment. When mixed with an artificial resin and moulded under heatand pressure this material results in a moulding of yellowish colour`and milky-opaque appearance. In order to obtain a material giving amoulding of lighter colour and greater translucency, this productrequires further treatment, consisting of refining and bleaching. Thistreatment is preferably effected in the following manner:

Firstly, the material is treated for 16 to 24 hours with an ammoniacalsolution of say 0.5% strength. This treatment results in making theproduct lighter in colour as Well as causing a loosening and slightswelling of the keratin substance without however chemically attackingthe substance. The subsequent bleaching treatment with a reducing agent,or a combination of agents, has a far better effect than without apreceding ammonia (alkali) treatment.

It is undesirable to employ sodiumor potassium-hydroxide as an alkalineagent, as these chemicals-even in dilute solutions-tend to causesplitting of the protein substance, especially of the cystin. Cystin,which is contained in hoofs up to 15% is easily split up by alkali(caustic) evolving hydrogen-sulphide. When neutralized with acid,colloidal sulphur is formed. The protein is partly destroyed down to thestructure of animal glue. This results in a considerable darkening ofthe moulding caused by oxidation and other reactions catalysed by theheat of the moulding process. We have ascertained that the pretreatmentof the hoof substance with dilute (1t/10) ammonia solutions results inthe required loosening of the particles, Without the above mentioneddisadvantages of NaOH and KOH. Even 411. solutions of ammonia do notcause visible destruction of the keratin, whereas, NaOH or KOI-l woulddestroy the keratin irreversibly. If the material pretreated in this wayis mixed with a resin and pressed under heat, the moulding is of greatertranslucency and lighter colour than the untreated material. Themouldtreatment: v

I Example 1 Hoofmeal A parts by weight" 550 0.88 ammonia` l v parts 10Water do 1800 are; agitatedfor 16 to: 24V hours and the watersubsequentlyvremoved by centrifuging. The material can be` washed ifrequired, before placing inf 1500 partsv of'jwater. The' water, which isslightly alkaline to litmus,g isV neutralised with iron-freehydrochloric acid, and 15 to 20 parts of sodium formaldehyde sulphoxylicacid are added under constant stirring. The pI-I value of the solutionis then lowered to approximately 4.5 to 5.5 by the addition of acid. Bythe acidification of the solution the reducing power of the agent isaccelerated, and certain impurities are dissolved in the acid medium. Itis necessary to adjust the pH value which, at the beginning of theprocess, has a tendency to rise. The material is then centrifuged,washed with water until the pH value of the washing water remainsslightly below '1. The material is finally dried at 45-50 C.

Example 2 25 parts of hoofmeal in 125 parts of n/10 ammonia aremaintained at room temperature for 6 hours, with constant stirring.After neutralising and washing, the water is removed and the materialput into 90 parts of water at approximately 90 degrees C.r in which 0.7to 1.5 parts of sodium formaldehyde sulphoxylic acid are dissolved. Thetemperature is kept up to 70 to 80 C. for 2 to 6 hours. Steaming of thematerial must be prevented. The material is then centrifuged, washedwith water and dried at 45 C.

Example 4 As in Example 3, with the exception that the pH value of thebleaching solution is brought down to from 5 to 3 as may be foundnecessary. It has to be borne in mind that We are dealing with anorganic material which Varies with the origin of the cattle, andconsequently the methods employed have to be varied within certainlimits.

All the materials obtained by the methods described in the examples whenmoulded under heat and pressure show a great improvement in colour andtranslucency. They can be moulded into many articles, of limited size,as for example small electrical insulators or fittings, buttons andslides. The mouldings have to be hardened in formaldehyde solutions buttheir resistance to Water if moulded without additions of resin, israther poor.

A simple reducing treatment following When "incorporated into:amlnolformaldehyde resins, as for instanceureaormel'am'ine formaldehydecondensation. products; moulding powders are obtainedwhich can bemouldediat' 145 to C., and a-pressure of ltoll/z tons per square inch.The resulting mouldings.- are of I great clarity witnout having lostvtheir hornlikeappearance,

are highly resistant tewater, andy combine the.

hard brilliancy of the finish-'of asyntheticresin with the soft sheen ofthe natural horn. The mouldings show all the characteristics of theamino-aldehyde resins andcan-be machinedY and turned to any requiredshape. The-perfect uni'- formity of the material makes it possible toobtain the most delicate shades in translucent,

semi-transparent and opaque varieties by the usual dyeing methods. Themoulding. powder has a good ow and cures satisfactorily.

When mixed with phenol-formaldehyde resin the moulding 'powdercan-bedyed to a greater variety of--shades than the usual woodorcellulose-filledA moulding compounds.

Although` hooishafve` been referred to as the preferred raw material forthe ground keratin, horns and other natural materials rich in keratincan be used, but the best quality products are generally made from hoofsin the manner hereinbefore described.

We claim:

1. A process of preparing keratin meal for use in moulding compositions,consisting in crushing natural animal products of the class consistingof horns and hoofs composed mainly of keratin, and subjecting thecrushed product to a plurality of stages of grinding increasing inintensity from one stage to another, and to intermediate sieving,wherein loosened foreign matter is eliminated, the overs from the laststage of sieving comprising keratin meal in a relatively high degree ofpurity, steeping the keratin meal in dilute ammonia for a period ofseveral hours duration, separating the alkaline solution from thekeratin meal, placing the separated product in Water, neutralizing itwith a weak solution of acid, and stirring into the liquid a reducingagent having bleaching properties containing a substance selected fromthe group consisting of sodium formaldehyde sulphoxylic acid and sodiumhyposulphite, separating the product from the liquid, washing and dryingit.

2. A process of preparing keratin meal as claimed in claim 1 wherein thereducing agent comprises sodium formaldehyde sulphoxylic acid.

3. A process of preparing keratin meal as claimed in claim 1 wherein thereducing agent comprises sodium formaldehyde sulphoxylic acid and sodiumhyposulphite.

4. A process of preparing keratin meal for use in moulding compositions,consisting of crushing natural animal products of the class consistingof honrs and hoofs composed mainly of keratin, and subjecting thecrushed product to a plurality of stages of grinding increasing inintensity from one stage to another, and to intermediate sieving,wherein loosened foreign matter is eliminated, the overs from the laststage of sieving comprising keratin meal in a relatively high degree ofpurity, steeping the keratin meal in dilute ammonia for a period ofseveral hours, centrifuging to separate out the alkaline liquid, addingwater to the product, neutralising with iron-free hydrochloric aci-d,adding a reducing agent having bleaching properties containing asubstance selected from the group consisting of sodium formaldehydesulphoxylic acid and sodium hypo'sulphite,` adding more acid to lowerythe pH value of the liquid to 5.5 or less, centrifugng the product,washing and drying the product.

5. A process of preparing keratin meal for use in moulding compositions,consisting in crushing natural animal products of the class consistingof horns and hoofs composed mainly of keratin, and subjecting thecrushed product to a plurality of stages of grinding increasing inintensity from one stage to another, and to intermediate sieving,wherein loosened foreign matter is eliminated, the overs from the laststage of sieving comprising keratin meal ina relatively high degree ofpurity, steeping the keratin meal in dilute ammonia for a period ofseveral hours duration, adding a reducing agent having bleachingproperties comprising a mixture of sodium hyposulphite and sodiumformaldehyde sulphoxylic acid, and subsequently adding acid to reducethe pH value of the liquid below 5.5, separating the product from theliquid, washing and drying it.

RICHARD NEIGER. VACLAV NACHAZEL.

' REFERENCES CITED The following referenlces are of record in the fileof this patent:

UNITED STATES PATENTS Number Name Date 687,219 Gai Nov. 26, 1901 867,167Stiegelmann et al. Sept. 24, 1907 1,594,633 Schar Aug. 3, 1926 2,072,665Campbell et al Mar. 2, 1937 FOREIGN PATENTS Number Country Date 423Great Britain Apr. 1l, 1856 OTHER REFERENCES Lehmann: Melliand TextilBerichte, vol. 24, pp. 1 to 5 (Jan. 1943).

